The prevalence of neurocognitive disorders that result from HIV infection of the central nervous system (CNS) is increasing. Macrophages, the primary target for HIV within the CNS, play a very central role in HIV-induced neuropathogenesis. They are resistant to the cytopathic effect of HIV and produce virus for longer periods of time thus serving as viral sanctuaries. Drugs of abuse such as methamphetamine (Meth) have been shown to further exacerbate HAND by increasing viral replication in the macrophages. If effective treatment regimens for HAND are to be developed a better understanding of viral pathogenesis in these reservoirs for potential therapeutic treatment strategies is needed. To understand the molecular mechanisms underlying neurotoxicity by HIV-1 and Meth in the brain, the current proposal focuses on one important and emerging player called extracellular vesicles (EVs) also often referred to as ?exosomes? or ?microvesicles? in HIV pathogenesis. Our preliminary studies indicate that Meth can increase EV biogenesis and release from macrophages. Thus the central hypothesis of this proposal is to further understand how Meth in conjunction with HIV affects EV biogenesis and release from macrophages and consequently can exacerbate HIV associated neuropathogenesis. We will investigate this hypothesis under two specific aims: Specific Aim 1 will identify the role of Meth in EV biogenesis and release from macrophages through deciphering its effect on endosomal-sorting complex required for transport (ESCRT) dependent and independent pathways. Specific Aim 2 is designed to study the effects of EVs in HIV disease progression and latency in the CNS using a humanized mouse model by employing a series of biochemical and cellular assays. Successful completion of this project will provide important new information on how Meth influences EV biogenesis and as well as further our understanding on the impact of the released EV cargo from HIV infected macrophages on re-activation and latency in CNS.